He faces up to life in prison if convicted.
As he was led out of the courtroom in shackles, the skinny teen turned briefly to offer a small smile to his older brother seated in the gallery.
Third District Judge Robin Reese bound over the case against Brackett, ruling that prosecutors presented enough evidence to show probable cause.
Reese based his decision largely on testimony from an October hearing at which Brackett's mother, Gina George, tearfully testified about her husband's death and son's arrest.
Gina George told the judge that she was in the bathroom on Sept. 13, 2012, when she heard a bang. She was the only other person home with her son and 52-year-old James Michael George.
"I was in the bathroom the whole time until I heard gunfire. Then I was in a panic," Gina George said. "I saw my husband's head toward the bathroom door, facedown in a puddle of blood."
Brackett told police that he and his stepfather had been arguing in their home, near 3700 South and 6800 West, about school and his efforts to obtain his GED. He changed his story twice, officers said.
First he said he was in his room when his stepfather was shot and had nothing to do with the shooting. Later, police said, Brackett recanted and told officers he had pulled the trigger himself.
According to officers who interviewed the boy, Brackett said the two had been arguing when George lunged at him and then turned into the bedroom, where the family stored several firearms.
"He thought Jim was going to get his gun," testified West Valley City detective John Pittman. "So, [Rosco] went to retrieve a gun he knew was in the living room next to the front door."
He fired one warning shot over his stepfather's head, Brackett told the detective.
That's when James George allegedly wheeled around, exclaimed, "What the hell," and grabbed the boy. He hit him several times, Brackett told police, though officers were unable to find any bruising or marks on the boy's body.
James George suffered gunshot wounds to the head. He died the next morning in a hospital.
Family members of the victim testified in October that the defendant and his stepfather had a "strained" relationship.
The mother told Reese her husband never much cared for her son, whom he saw as "baggage."
She characterized her husband as controlling and demanding a man who did not want her to work and refused to let her leave the house after he returned home for the evening.
At the time James George was killed, the woman said, she had been planning to leave with her son and return to her family in Missouri.
Brackett continues to be held in the Salt Lake County jail, with bail set at $1 million.
Prior to the Sept. 13 shooting, Brackett had one run-in with the law, according to juvenile court records. He was referred to a juvenile court May 2010 for shoplifting less than $299 worth of property.
He is next scheduled to appear in February before Judge Katie Bernards-Goodman.